Hands-On Data Analysis with NumPy and pandas

Filling missing information

We can use the fillna method to replace missing information in a series or DataFrame. We give fillna an object instructing the method how this information should be replaced. By default, the method creates a new DataFrame or series. We can give fillna a single value, a dict, a series, or a DataFrame. If given a single value, then all entries indicating missing information will be replaced with that value. A dict can be used for more advanced replacement schemes. The values of the dict could correspond to, say, columns of the DataFrame; think of it as telling how to fill missing information in each column. If a series is used for filling missing information in a series, then the past series tells how to fill particular ...